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Mintronics: Menta 


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Mintronics: Menta 

Written By: Maker Shed 

y* TOOLS: 

Desoldering tool (1) 

optional, for fixing your soldering 

Helping hands tool with magnifier (1) 
optional but extremely helpful 

Multimeter (1) 

optional but helpful for checking voltages 
and continuity 

Solder (1) 

Soldering iron (1) 

Wire cutters (1) 

aka flush/diagonal cutters 


Mintronics: Menta Kit (1) 
Includes all the following parts: 

Microcontroller (1) 

preprogrammed with Arduino bootloader 

IC socket. 28 pin (1) 

Ceramic oscillator (1) 

for cheap, reasonably precise 
timekeeping — X1 

DC power jack (1) 

Diode. 1N4001 (1) 

Voltage regulator IC (1) 

Voltage regulator IC (1) 

Capacitor, ceramic (4) 
C1 C2C3C4 

Capacitor, electrolytic (1) 

Capacitor, electrolytic (2) 

Resistor (1) 

(brown black orange gold) — R1 

Resistor (2) 

(brown black red gold)- 



i Fn r-n 

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Mintronics: Menta 

\ - / 


Switch (1) 

Header, male (1) 

Header, male (1) 

Jumper (1) 

Header, female (2) 

Header, female (2) 

Bumpers (4) 

Printed circuit board (PCB) (1) 


The Mintronics: Menta is a unique Arduino-compatible microcontroller kit. It features a 
handy, on-board prototyping space and is specifically designed to use the included mint tin 
as an enclosure! This makes it perfect for logging applications and on-the-go development. 
The prototyping area is perfectly sized for one of our mini breadboards (not included) so you 
can wire circuits without soldering. Ready for some expansion? The Menta can be used with 
all Arduino-compatible shields. 

The Mintronics: Menta kit was designed in NYC by open source hardware pioneer Adafruit 
Industries, in partnership with MAKE and Maker Shed. 

Note: Requires FTDI programmer (like the FTDI Friend ) and soldering. 

(Assembly photos and text are used with permission from Adafruit Industries ) 

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Mintronics: Menta 

Check the parts list and verify that you have everything. Then heat up your soldering iron 
and clear off your desk. 

Place the circuit board in a vise or helping hands tool so you can easily work on it. 

• Component R3 is a 1,000 ohm (1kQ or 1K) resistor, indicated by brown, black, red, and 
gold stripes. Don't confuse it with the 10K resistor which has an orange stripe. If you're not 
sure, use a multimeter to check! This resistor sets the brightness of the red LED that's 
used by the Arduino to indicate when it is bootloading (downloading sketches). 

• Bend the resistor into a "staple" shape and place it in the slot on the PCB marked R3, right 
over the resistor-shaped image. Resistors do not have polarity so no worries about putting 
it in backwards; they work the same either way. 

• Bend out the long metal leads so the resistor sits flat agains the board, and flip the PCB 

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Mintronics: Menta 

Step 3 — Solder resistor R3 

Now we will solder in the first part. Heat up your soldering iron (about 700 degrees F is 
common but you may need to adjust it higher for lead-free) Using your soldering iron tip, 
press and heat both the pad (the silver ring around the hole) and lead (wire) at the same 
time for 2 or 3 seconds. Then poke the end of the wire into create a nice solder joint. Do 
this for both leads. 

Using your diagonal cutters, cut off the long leads just above the solder joint. 

R2 is another 1 K resistor (brown black red gold) that's used to set the brightness of the 
green LED, which indicates when the board is correctly powered. R1 is a 1 0K resistor 
(brown black orange gold) that's part of the reset circuitry — it keeps the Arduino chip 
active when you want to, and helps reset it when the RESET button is pressed. 

Bend and place them in the slots labeled R2 and R1 . 

Flip over the PCB and solder the 2 resistors. 

Clip the 2 resistors' leads. 

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Mintronics: Menta 

• Ceramic capacitors are used for high-frequency filtering and noise reduction. They'll keep 
the power supply system stable even if you're doing high-current stuff like motors, or really 
big LEDs. 

• The ceramic capacitors are yellow blobs; place them in locations C1, C2, C3, and C4. Like 
resistors, they're not polarized, so they can be inserted either way and will work fine. Bend 
out the leads to keep them flat against the PCB. 

• Solder all the capacitor leads and clip them short. 

The RESET pushbutton is what you'll press to reset the Menta, say if you want to start the 
program over. 

Buttons are symmetric, and they only fit the holes one way, so just press it into place and 
it should snap in. 

Solder all 4 legs of the button. There's no need to clip them as they're already quite short. 

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Mintronics: Menta 

• Now you'll place the first nonsymmetric component, a diode! The diode conducts current in 
one direction only, so we use it for protecting the Menta — it makes sure we don't connect 
negative voltages into the DC plug that could damage or destroy the electronics. This 
diode is a 1N4001 model, an extremely common power diode that can handle over 1 amp 
of current. 

• Diodes have a stripe to indicate the cathode — this one has a silver stripe. Make sure the 
silver stripe matches the little white stripe on the PCB (in this image, it's on the right-hand 
side). Double-check that you get this right because otherwise nothing will work! 

• Solder in the diode and clip the leads. 

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Mintronics: Menta 

• This component takes a high 
voltage (from 7V DC to 25V DC) 
and regulates it down to 5V. The 
Menta circuitry requires a nice 
clean 5V DC to run; any more 
could burn it up. This regulator is 
the very common 7805 type in a 
big package that can handle up to 1 
amp of current. 

• Place it flat on its back so it 
matches up close to the image on 
the PCB, making sure you can read 
the part number on top. Don't worry 
if it doesn't line up perfectly; you 
won't use the hole in the regulator 
for anything (it can be used for heat 
sinks but it's not necessary here). 

• Solder in the 3 legs and clip them 

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Mintronics: Menta 

These are the beefy versions of the ceramic capacitors we already placed. Ceramics are 
good for high-frequency noise, and electrolytics are good for low-frequency noise; that's 
why we team them up together to cover all frequencies. 

Electrolytic capacitors are polarized — they must be put in the correct way or they will be 
damaged so be super careful here. Capacitors have one leg that's longer than the other, 
this is the positive lead. Place the positive lead in the hole marked with a tiny + next to it. 
See the images of how to place the 3 capacitors. C5 is a 25V 47uF cap (it's bigger than the 
others) for filtering the incoming power from the DC power jack. C6 and C7 are smaller 
6.3V 100uF for filtering the 5V and 3.3V supplies. 

After you've triple-checked the polarity of the capacitors, flip over the PCB, solder them in, 
and clip the leads. 

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Mintronics: Menta 

Step 10 — Solder the LEDs 

• The indicator LEDs are the Merita's way of telling you what's going on. LEDs are light- 
emitting diodes — which means that like the 1N4001 they have a polarity and won't work if 
placed backwards. Like capacitors, the also have a longer wire that indicates the positive 
lead. Place this wire in the hole marked with a +. 

• First place the green LED; this is the power indicator LED. Then place the red LED; this is 
the "pin 13"/bootloading indicator LED. 

• Solder both LEDs in, and clip the leads. 

Step 11 — Solder the power jack. 

• Now you can place the big power jack. This is how you'll plug in a battery or power 

• The power adapter has big flat pins, so that it can pass a lot of current and also so that it 
will stay mechanically attached to the board. Use a lot of solder to fill in the big pads 

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Mintronics: Menta 

Step 12 — Solder the crystal XI 

The 16.00MHz crystal, X1, is what lets the Menta chip run at a brisk 16 million clocks per 

This oscillator comes in an orange shape with 3 pins. Luckily, it's symmetric, so just place 
it any way you like. 

Bend the leads, flip over the PCB, solder it in, and clip the leads. 

Step 13 — Prepare the male breakaway headers. 

Now you're at the toughest part of the kit. Luckily you've done so many parts so far, you 
should be pretty comfortable with the iron. The problem with headers is that the leads are 
so short you can't bend them when flipping the PCB over, so you'll need to use tape or 
playdough or tack to hold them in place for soldering. 

Take the long stick of "breakaway" male header and break off one 6-pin and one 3-pin 
piece. Keep the rest for a future project; it's handy stuff. 

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Mintronics: Menta 

Step 14 — Solder the male headers 

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Place the 6-pin piece into the spot next to the green LED. Make sure the short legs are 
sticking down into the PCB and the long legs are sticking up. This is the programming 
header, where you'll connect an FTDI cable or FTDI Friend to reprogram the Menta. 

Place the 3-pin piece below that, in the PWR_SEL spot. This is for selecting whether you 
want to power from the FTDI cable or from the DC jack. 

Finally, find the 2x3 header and place it in the ICSP spot. This is where you can connect 
an AVR programmer such as a USBtinyISP, Dragon, etc. to program the AVR chip. 

Use your favorite tape to hold the parts in place. Masking tape works better than cellotape, 
but use what you have. 

Flip over the PCB, check that the headers are still in place, and solder all the short leads 
in. You won't need to clip them because they're very short already. 

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Mintronics: Menta 

Step 15 — Test your 5V DC power, 

• Place the jumper onto the PWR_SEL header on the right-hand side, in the DC position — 
this indicates that you'll be powering it via the big DC jack. 

• To test your 5V DC power, find a power adapter 7V DC or higher, with a 2.1 mm jack and 
center-positive polarity (these are nearly standard), and plug it in. With the jumper in 
place, you should see the green LED light up. If not, something is wrong — either the LED 
is in backwards or your power supply isn't working. Go back and check your work until you 
can figure out what happened. 

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Mintronics: Menta 

Step 16 — Solder the 3.3V regulator and 28-pin IC socket, 

Once you know the 5V power supply is working, you can solder in the 3.3V regulator. This 
will let you power the many 3.3V sensors and accessories out there, a nice little extra! The 
chip is the MCP 1700-330 — you should be able to see this marking on its face. It can 
supply up to 250mA, plenty for nearly any device you'll be using. Place the chip so that its 
flat face matches the flattened image on the PCB. 

Next, place the 28-pin socket next to it. This socket is a mechanical "holder" for the 
ATmega328 chip that drives the Menta. We socket it for a few reasons: to protect the chip, 
to make it easier to replace in case of damage, and so that you don't have to worry about 
accidentally soldering it in backwards. (If you mess up on the socket, it's a lot easier to fix 
than if you do the same with the chip.) 

The socket has a little half-moon notch on one end. Make sure this notch matches the 
notch marked on the PCB — it will help you align the chip later. If you get this wrong, don't 
try to remove the socket, just keep going. 

Solder in the 3.3V regulator and all 28 pins of the socket, and clip the regulator leads. The 
socket doesn't need to be clipped. 

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Mintronics: Menta 

Step 17 — Place the ATmega328 chip, 

• Now we can place the ATmega328 chip — the brains of the Menta. Chips come with their 
legs in an A shape, but we want them in more of an H shape. Pick the chip out of the 
antistatic foam and holding it by the ends, bend the leads against the table to flatten them 
parallel to each other. Once they're straight, they're easy to fit into the socket. 

• Make sure you fit the ATmega328 chip in the right way, as it's symmetric. One end has a 
half-moon cut out of it — this should be on the left side in the photos, matching with the 
notch in the socket and the notch marked on the PCB. 

Step 18 — Test the ATmega328 chip and crystal. 

Now you can do a second test, to 
check whether the chip and crystal 
are working right. Plug in the board 
again to the DC power and press 
the Reset button. You should see 
the red LED flashing a few times. 
Every time you press the button it 
should flash again. Once you're 
happy, remove the DC power and 
you can finish up. 

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Mintronics: Menta 

Step 19 — Solder female headers for shields (optional) 

This step is optional, but if you want to plug in shields, you'll want to complete it. If you 
want a more compact Menta, skip it! 

Like the Arduino, the Menta can accept "shields," pluggable add-ons to increase its 
functionality. If you want this ability, grab the two 8-pin female headers and two 6-pin 
female headers and place them in the outer pins marked "Digital I/O" and "Analog I/O" — 
there are 2 sets of pins so be sure to use the OUTER ones! 

If you have a shield handy, you can plug it in now to test the fit, and hold the female 
headers straight while you solder them in. Otherwise use tape, or if you're dextrous, hold 
the header with one finger while soldering. 

Step 20 — Add bumpers. 

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# Finally, you can finish your kit by 
placing the 4 rubber bumpers over 
the mounting hole spots. These wi 
keep the Menta off your desk to 
avoid scratching it or accidentally 
shorting it against a piece of wire. 

© Make Projects 

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Mintronics: Menta 

Step 21 — You're done! 

• That's it! You're done! Now you can 
read the User Manual for details on 
how to upload your favorite Arduino 

(Assembly photos and text are used with permission from Adafruit Industries ) 

This document was last generated on 201 3-01 -1 8 03:22:41 PM. 

© Make Projects 

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